1. Field of the Invention
This invention relates generally to the production of cushioned articles and, more particularly, to a method of making a cushioned bathroom article having a laminar structure.
2. Description of the Prior Art
Cushioned bathroom articles such as bathtubs, shower stalls, sinks, etc. are known in the art. These articles are typically formed as a laminated structure having a flexible polymeric outer layer, typically of vinyl, a base, typically made of a fiberglass reinforced polyester resin, and a cellular foam sandwiched between the flexible polymeric outer layer and the base. Such cushioned bathroom articles are comparable in appearance to conventional steel, iron or porcelain coated bathroom articles. However, the foam provides improved thermal and acoustic insulation over such conventional fluid receptacles. Additionally, when such a laminar structure is applied in the formation of a bathtub, the combination of a flexible polymeric outer layer with a foam under layer reduces the likelihood of someone slipping in the tub and, in the event someone does slip, cushions the fall of a person in the tub.
For a number of reasons, such prior art cushioned bathroom articles have not found widespread acceptance. Perhaps the most important of these reasons is that the cushioned bathroom articles known in the prior art are not able to withstand the rigors of actual use over prolonged periods of time. Additionally, these cushioned bathroom articles typically cost substantially more than conventional, non-cushioned articles. The relatively greater cost for the cushioned articles is due to several reasons, including the increased costs and manufacturing time required for preparation and fabrication of the cushioned components and also the large number of rejects produced in the highly sensitive laminar manufacturing process.
An example of a prior art cushioned bathroom article is described in U.S. Pat. No. 4,289,717 to Bortz. The Bortz patent discloses a fabrication method in which a base is formed by a two-part mold resin injection process. A vinyl containing outer skin and a foam layer are combined with the base to form a cushioned tub. The Bortz patent is typical of the known manufacturing processes for producing cushioned articles. However, these known methods, such as the method disclosed in the Bortz patent, have several distinct disadvantages.
Firstly, the two-part mold resin injection process used to form the base of the tub is a costly and time-consuming process. The two part molds required for this process must be made to a high degree of tolerance and, therefore, are costly to purchase.
Additionally, the components used to form the flexible skin contain a volatile carrier solvent which must be volatilized after application. The curing of these volatile solvents has a tendency to form small, trapped bubbles in the skin which adversely impact upon the overall look and structural integrity of the finished article. Additionally, these volatile solvents are generally toxic and flammable and, therefore, the article under manufacture must be quarantined during evaporation of these solvents.
Further, the flexible composite outer polymeric skin includes vinyl. When vinyl is used as the outer skin, breakdown of this skin can occur under the rigors of actual use due to the physical properties of the flexible skin, such as tensile strength, elongation strength and abrasion resistance. Vinyl tends to lose plasticizer over time, resulting in a hardening of the flexible polymeric outer skin. The curing times required for vinyl resins also contribute significantly to the length of the processing time for the tub.
An additional reason that prior cushioned articles have not found widespread acceptance in the market is due to the problems encountered in the molding process. For example, the process described in the Bortz patent produces an unacceptably high number of rejects due to the leakage of foam between the base and the flexible composite skin during the manufacturing process.
Therefore, it is an object of the invention to provide a method of manufacturing a cushioned article in which the disadvantages of the solvent based coatings of the prior art are eliminated. It is a further object of the invention to provide a manufacturing method which decreases the number of rejects in the manufacturing process and also decreases the overall costs of the manufacturing process. It is also an object of the invention to provide an improved manufacturing process which reduces the length of time required to fabricate a cushioned article.